Solution 2: (Recommended) If the above solutions isn't working, we suggest that you upgrade your phone the official Windows10 operative system by pressing on this link: https://www.microsoft.com/en/mobile/windows10?linkId=22420781

Solution 3:If Windows10 is not yet available for your device, please upgrade to Windows10 Insider. Follow the steps below.

1. Uninstall Truecaller! Sign up for the Windows Insider Program, if you haven't already.

2. Open this webpage from your phone, and then click Download the Windows Insider app. You can also search for the Windows Insider app in the Store from your phone. https://www.microsoft.com/sv-se/store/apps/windows-insider/9wzdncrfjbhk

3. Once it finishes downloading, open the Windows Insider app on your phone and follow the instructions to install Insider Preview. You'll have the option to choose whether you want to get new builds fast or slow. Choose Fast to get updates as soon as they're available, or choose Slow to wait until builds are a little more stable before you update.

4. Once the Windows Insider is installed, please install Truecaller version 6.xx from Store.